Machine gun



Feb. 22, 1938.

F. D. HOPPERT ET AL 2,108,817

MACHINE GUN Filed June 17, 1956 Invent or; Filsar I] Hc| p pErt WilliamEJ311411 E1arE1-1tEE-5i1-npsun Att Elm-LEV I Patented Feb. 22, 1938Application June 17. 1986, Serial No. 85.698

2 Claims. (61. 42-75) (Granted under the act of March 3, 1883, as

amended April 30, 1928: 370 0. G. 757) The invention described hereinmay be manuiactured and used by or for the Government for governmentalpurposes, without the payment to us of any royalty thereon.- Thisinvention relates to a machine gun. For the purpose of instruction it iscustomary to adapt guns to fire sub-caliber or low pressure ammunition.An adaptation of this character for machine guns is shown in PatentsNos. 2,027,892 and 2,027,893 of January 14, 1935, in which the standardBrowning machine gun of Patent No. 1,293,021 of February 4, 1919,designed to fire a .30 caliber cartridge developing high pressure, isarranged to fire a .22 caliber l5 cartridge developing low pressure,provision being made to increase the kinetic efiect of the gases so thatsuflicient energy will be available to actuate the breech bolt and thecartridgefeeding mechanism.

Becauseof the diflerence in length and diameter of the caliber .30 and.22 cartridges, it was necessary in the device of the patents to somodiiy the breech bolt, the cams on the receiver and the feedingmechanism that the conversion is expensive and of more or less permanentnature to be performed at an arsenal.

The purpose of the present invention is to provide an arrangementwhereby the conversion of the gun to fire a caliber .22 cartridge andits conversion to fire a caliber .30 cartridge may be readilyaccomplished by substitutable parts and without structural modificationof the original gun.

The distinguishing feature of the invention is the provision of a holdersimilar in shape and size'to the case of a caliber .30 cartridge, theholder being adapted to carry a caliber .22 cartridge for which itserves 'as a firing tube, and which is fed, extracted and ejected in theconventional manner.

A further object is to provide means for looking the gun barrel invarious longitudinal positions for the purpose of establishinghead-space adjustment.

To these and other ends, the invention consists in the construction,arrangement and combination of elements described hereinafter andpointed out in the claims forming a part of this specification.

A practical embodiment of the invention is illustrated in theaccompanying drawing, wherein:

Fig. 1 is a view partly in side elevation and partly in section of thebreech end of a machine 5 gun with the parts in firing position.

Fig. 2 is a similar view with the parts in position of full recoil.

Fig. 3 is a longitudinal sectional view of the .muzzle end of the gun.

Fi 4 is a detail view in side elevation and partly in section of thepiston.

Fig. 5 is a longitudinal sectional view of the barrel cylinder.

Fig. 6 is a longitudinal sectional view of the iiiolder carrying a roundof sub-caliber ammuni- Fig. 7 is a sectional view Fig. 3.

The gun illustrated in the drawing is of the Browning type and includesthe usual receiver 5 having the trunnion block 6, cartridge feedway 7-,and belt feeding slide 8. In the standard gun the barrel is attached toa member 9 usually referred to as the barrel extension and thisextension member is mounted for limited movement within the receiver. Itcarries a slidable breech bolt i9 having the customary extractor leverit which is provided for withdrawing a cartridge from the belt in thefeedway and lowering it into thegroove !2 in the front face of the bolt.

A cylinder i3 fitting in the trunnion block 6 of the receiver has athickened front portion with an axial passage i4 whereby it is mountedon and'threadedly attached to the rear end of the gun barrel IS. Thefront part of the passage is provided with threads it for engagement ofthe threaded portion ll of the barrel.

The muzzle end of the barrel passes through the front end cap l8 of thewater jacket i9 and is held stationary by means of a looking on the line1-1 of nut 29 and an adjusting nut 2i threaded on the barrelrespectively on the outer and the inner side of the cap l8. The nut 20retains the usual packing gland 22 in the socket 23 of the cap. The nut28 is formed with a projecting lip 24 adapted to engage the end cap l8and be restrained thereby against rotational movement. The muzzle of thebarrel is formed with surfaces indicated at 25 for the application of atool which is to be used-in turning the barrel to adjust itlongitudinally with respect to the breech bolt.

A piston 26 threadedly attached to the extension member 9 has its frontportion arranged to slide in the rear portion of the cylinder 13 in rearof the gun barrel I. The front end of the piston 26 is formed with adished face as at 21' and is adapted to engage an annular shoulder 28formed by the thickened front porpiston and expanding radially act onthe dished for obtaining headspace adjustment is the same as that of thestandard gun.

The piston is formed with an axial chamber 32 having a flare 33 at itsrear end and having a central tapered portion 34. A tubular holder 33similar in shape and size to the case of a caliber .30 cartridge isadapted to flt in the chamber 32. The holder carries a caliber .22cartridge 36 and serves as a loading member and a firing tube. As shownmost clearly in Fig. 6, the base 31 of the holder is formed with anannular recess 38 for receiving the rim 33 of the cartridge 36 so thatthe base of the cartridge is flush with the base of the holder. Theinterior wall of the holder is formed with a tapered seat 40 for theshoulder 4| of the cartridge 36. The holder has the usual cannelure 42whereby it is seized by the extractor lever II and held in the groove Hof the breech bolt.

A guide and stop unit 43 is placed in the cartridge feedway 1 and servesto properly position the holders 35 which are carried in a belt in lieuof the caliber .30 cartridges.

Because of the similarity of the holder 35 and the caliber .30 cartridgethe operations 01' withdrawing a holder from the feedway and insertingit in the chamber 32 of the piston 26 will be performed in the samemanner as in the standard gun.

When the cartridge 36 in the holder is struck by the firing pin 44, thebullet moves through the holder and then through the gun barrel IS. Thegases of the propellent charge travel out of the front face of thepiston and the annular shoulder 28 in the stationary cylinder I3 todrive the piston rearwardly. Since the piston is attached to theextension member 9 the latter will be driven rearwardly, and aftermoving a short distance as shown in Fig. 2 to accomplish unlocking ofthe breech bolt, it is locked in place in the usual manner, while thebreech bolt continues its movement in recoil to perform its usualfunotions of extracting the holder from the piston,

cocking the firing pin, withdrawing a loaded holder from the feedway andlowering it in the groove 12. During counterrecoil movement of thebreech bolt the loaded holder is inserted in the chamber of the pistonwhile the breech bolt trips the extension member 3 which moves intobattery. The empty holder which is ejected from the breech bolt isrecovered and repeatedly re used.

It is to be understood that the terms caliber .22 and .30 are relativeonly and that a large caliber piston cartridge such as the .45 mayequally as well be placed in the holder, or a caliber .30 cartridge witha reduced charge may be substituted for the holder.

We claim:

1. In a gun, a receiver, a Jacket on the receiver having a barrelsupporting memberv at its front end, a barrel mounted in said member andhaving a cylinder on its rear end mounted in the receiver, an adjustingnut on the barrel and having means engaging the rear part of thesupporting member whereby said nut is restrained against rotationalmovement, a locking nut on the barrel on the forward side of thesupporting member, an extension member slldable in the receiver, achambered piston carried by the extension member and working in thecylinder on the rear end of the barrel a collar on the piston engageablewith the rear end of the cylinderto limit forward movement of thepiston, said piston having an annular series of notches on itsperiphery, a spring carried by the extension member and engageable inthe notches, and a bolt mechanism actuated by the rearward movement ofthe piston.

2. In a gun, a receiver, a jacket on the receiver having a barrelsupporting member at its front end, a barrel having its breech endmounted in the receiver and its muzzle end passing through the frontsupporting member of the jacket, an adjusting nut threaded on the barreland having means engaging the rear part of the front supporting memberwhereby said nut is restrained against rotational movement, and alocking nut on the barrel on .the forward side of the front supportingmember.

FILSER D. HOPPERT. WILLIAM R. BULL. CLARENCE E. SIMPSON.

